JPH077640A - Video camera with electronic view finder - Google Patents

Abstract

PURPOSE:To provide a video camera with electronic view finder, which can prolong a time that can actually execute video recording with one battery by considerably reducing power consumption in a video recording waiting state compared to a recording state. CONSTITUTION:An analog output signal from an imaging device 12 is converted into a digital signal in an A/D converter 13. A standard television signal is generated in a digital signal processing circuit 14, and it is monitored by the electronic view finder 4 so as to be recorded in a recording part 3. A reference clock guided to an image pickup part is switched to the output of an oscillation circuit 18 at the time of the video recording state, and to the output of a 1/n frequency divider 21, namely, a frequency which is 1/n of the output frequency of the oscillation circuit 18 at the time of the video recording waiting state in connection to the state of an operation switch 6 switching between the video recording/video recording waiting states, namely, the video recording state of the video recording waiting state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera equipped with an electronic viewfinder capable of electronically monitoring a captured image.

[0002]

2. Description of the Related Art As a conventional example of a video camera equipped with an electronic viewfinder capable of electronically monitoring a photographed image, the one shown in FIG. 3 is typical. In the figure, reference numeral 1 denotes a lens 11, an image sensor 12, an image sensor drive circuit 15 for driving the image sensor 12, and an A / D converter 1 for converting an analog output signal from the image sensor 12 into a digital signal.
3. From the digital signal processing circuit 14 that processes the output signal of the A / D converter 13 to create a standard television signal and the like, and the sync signal generation circuit 16 that creates a sync signal to keep the entire video camera in sync. 2 is a clock generation circuit including a crystal oscillator 17 and an oscillation circuit 18,
Reference numeral 3 is a recording unit for recording the image signal captured by the image capturing unit 1, 4 is an electronic viewfinder for monitoring the image signal captured by the image capturing unit 1, and 5 is a system control circuit for controlling a state such as recording and recording standby. Reference numeral 6 is an operation switch for switching between recording and a recording standby state.

The reference clock generated by the clock generation circuit 2 is the image pickup device drive circuit 15 and the A / D converter 1.
3. The frequency of the reference clock is guided to the digital signal processing circuit 14 and the synchronization signal generating circuit 16, but is kept constant regardless of the state of the operation switch 6, that is, whether the recording state or the recording standby state, It is well known that the value is a value at which the frequency of the sync signal becomes a sync frequency according to the television standard, and varies depending on the number of pixels of the image sensor.

The power consumption of such a conventional video camera with an electronic viewfinder, particularly the image pickup section, will be examined. First, the ratio of power consumption of the digital signal processing unit of the image pickup unit 1 and other portions is about 3: 1 as shown in FIG.
Suppose In such a conventional video camera, since the performance and function of the image pickup unit 1 do not change between the recording standby state and the recording state, it is obvious that the power consumption is the same between the recording standby state and the recording state. It is a thing. Therefore, even when the video camera is used while switching between the recording standby state and the recording state as shown in FIG. 5 (generally used in this way), the power consumption does not change with time as shown by the curve 32 in FIG. It consumes the required power when recording. Therefore, in a video camera that is powered by a battery, the battery life (1
The electric power that can be supplied by one-time charging) is determined by the total time of the recording state and the recording standby state, and the actual recording time becomes short. For example, if the time ratio between the recording state and the recording standby state is 1: 1, the actual recording time will be half the battery life. Note that in FIG. 5, times t0 to t1,
t2 to t3 represent the recording standby state, and times t1 to t2 and t3 to t4 represent the recording state.

[0005]

The video camera provided with the conventional electronic viewfinder as described above has the above-mentioned problems. In other words, even in the recording standby state, it consumes the same power as in the recording state, so the battery life (in the case of a secondary battery, the power that can be supplied by one charge)
However, it is determined by the total time of the recording state and the recording standby state, and the time that can be actually recorded by one battery becomes short. For example, if the time ratio between the recording state and the recording standby state is 1: 1, the actual recording time will be half the battery life.

The present invention is intended to solve the above-mentioned problems, in which a video with an electronic viewfinder can be used, in which the power consumption in the recording standby state can be made much smaller than that in the recording state, and the actual recording time with one battery can be lengthened. The purpose is to provide a camera.

[0007]

To achieve the above object, the present invention provides an image pickup section in which at least a part of signal processing is performed by digital signal processing, and a clock generator for supplying a reference clock to at least the image pickup section. A circuit, an electronic viewfinder that monitors an image signal captured by the image capturing unit, an operation switch that switches between a recording state and a recording standby state, and a frequency of the reference clock in conjunction with a switching operation of the operation switch, The video camera with an electronic viewfinder is provided with a clock frequency switching circuit for switching to a frequency lower than the recording state in the recording standby state.

[0008]

According to the present invention, with the above configuration, the reference clock frequency of the image pickup unit is switched to a frequency lower than that in the recording state in the recording standby state, thereby reducing the power consumption of the image pickup unit, particularly the digital signal processing unit, and thereby reducing the recording standby state. The power consumption of the state can be significantly reduced compared to the recording state.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a video camera with an electronic viewfinder showing a first embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a lens 11, an image sensor 12, an image sensor drive circuit 15 for driving the image sensor 12, and an image sensor 12.
A / which converts the analog output signal from the
A digital signal processing circuit 14 that processes the output signals of the D converter 13 and the A / D converter 13 to create a standard television signal and the like, and a sync signal generator that creates a sync signal for maintaining the synchronization of the entire video camera. An image pickup unit composed of the circuit 16, 20 is a crystal oscillator 17, an oscillation circuit 18, an oscillation circuit 1
1 / n that divides the output signal of 8 into 1 / n (n: natural number)
A clock generation circuit including a frequency divider 21, a switching circuit 22 for switching the output of the oscillation circuit 18 and the output of the 1 / n frequency divider 21 by a signal from the system control circuit 5,
Reference numeral 3 is a recording unit for recording the image signal captured by the image capturing unit 1, 4 is an electronic viewfinder for monitoring the image signal captured by the image capturing unit 1, and 5 is a system control circuit for controlling a state such as recording and recording standby. Reference numeral 6 is an operation switch for switching between recording and a recording standby state. Then, the reference clock generated by the clock generation circuit 2 is guided to the image pickup element drive circuit 15, the A / D converter 13, the digital signal processing circuit 14, and the synchronization signal generation circuit 16.

The frequency of the reference clock is linked with the state of the operation switch 6, that is, the recording state or the recording standby state,
In the recording state, the output of the oscillation circuit 18 is switched, and in the recording standby state, the output of the 1 / n frequency divider 21, that is, the frequency of 1 / n of the output frequency of the oscillation circuit 18 is switched. That is, in the switching circuit 22, the terminal a is
In the recording standby state, the terminal b is selected.

The frequency of the reference clock in the recording state is a value at which the frequency of the synchronizing signal becomes a synchronizing frequency in accordance with the television standard as in the conventional example, and may vary depending on the number of pixels of the image pickup device. This is similar to the conventional example.

The power consumption of the image pickup section of such a video camera with an electronic viewfinder according to the present invention will be examined. In such a video camera of the present invention, the reference clock frequency is 1 / n of the recording state in the recording standby state.
However, since the power consumption of the CMOS digital circuit is generally proportional to its clock frequency, the power consumption of the digital signal processing unit of the image pickup unit is reduced to about 1 / n. Therefore, assuming that the ratio of the power consumption of the digital signal processing unit of the image pickup unit and the other portions in the recording state is about 3: 1 as in the conventional example, the power consumption of the entire image pickup unit is The power consumption ratio between the recording state and the recording standby state is
It becomes 1: (0.25+ (0.75) / n), and when n = 4, it becomes about 1: 0.44. Therefore, when the video camera is used while switching between the recording standby state and the recording state as shown in FIG. 2 (generally used in this way), the power consumption is as shown in the curve 31 in the recording standby state. It changes depending on the recording state, and when in the recording standby state, it consumes less power than in the recording state. Therefore, in a video camera that supplies power from a battery, the life of the battery (in the case of a secondary battery, the power that can be supplied by charging once) is not the total time of the recording state and the recording standby state, but the recording time. Since the time is determined closer to the time of the state, the time that can be actually recorded becomes longer than that of the conventional example. For example, when the time ratio between the recording state and the recording standby state is 1: 1 and the power consumption ratio between the recording state and the recording standby state is 1: 0.44, the conventional example of the actual recordable time and the present invention. And, 1: 2 // (1 + 0.44) = 1: 1.
39. That is, the recording time can be about 1.4 times longer than that of the conventional example. Note that in FIG. 2, times t0 to t
1, t2 to t3 are in a recording standby state, times t1 to t2, t3 to t4
Indicates the recording state.

In the embodiment of FIG. 1, the frequency of the reference clock is switched so that the oscillator circuit 1 can be used in the recording state.
8 is output to 1 / n frequency divider 2 which divides the output signal of the oscillation circuit 18 into 1 / n (n: natural number) in the recording standby state.
However, the present invention is not limited to this configuration, and it is obvious that the present invention can be realized by lowering the reference clock frequency in the recording standby state with respect to the recording state.

[0015]

As described above, according to the present invention, with a simple configuration, the reference clock frequency of the image pickup section is switched to a frequency lower than the recording state in the recording standby state, and particularly in the digital signal processing of the image pickup section. By reducing the power consumption of the unit, the power consumption in the recording standby state is significantly lower than that in the recording state, and it is possible to obtain a video camera with an electronic viewfinder that can record for a long time with one battery, and its practical effect is great. .

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a video camera with an electronic viewfinder according to the present invention.

FIG. 2 is a diagram showing temporal changes in power consumption of a video camera with an electronic viewfinder according to the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional video camera with an electronic viewfinder.

FIG. 4 is a diagram showing power consumption ratios of a conventional video camera with an electronic viewfinder and a video camera with an electronic viewfinder of the present invention in a recording state.

FIG. 5 is a diagram showing a temporal change in power consumption of a conventional video camera with an electronic viewfinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image pickup section 3 Recording section 4 Electronic viewfinder 5 System control circuit 6 Operation switch 11 Lens 12 Solid-state image sensor 13 A / D conversion circuit drive circuit 14 Digital signal processing circuit 15 Image sensor drive circuit 16 Synchronous signal generation circuit 17 Crystal oscillator 18 oscillator circuit 20 clock generator circuit 21 1 / n frequency divider circuit 22 switching circuit

Claims (2)

[Claims] 1. An image pickup unit in which at least a part of signal processing is performed by digital signal processing, a clock generation circuit for supplying a reference clock to at least the image pickup unit, and an image signal picked up by the image pickup unit is monitored. An electronic viewfinder, an operation switch for switching between a recording state and a recording standby state, and a clock frequency for switching the frequency of the reference clock in conjunction with the switching operation of the operation switch to a frequency lower than the recording state in the recording standby state. A video camera with an electronic viewfinder, comprising a switching circuit. 2. A clock frequency switching circuit divides a fundamental frequency oscillator circuit output and the fundamental frequency oscillator circuit output by 1 /
2. The video camera with an electronic viewfinder according to claim 1, wherein the video circuit with an electronic viewfinder is configured to switch between an output of a frequency dividing circuit that divides the frequency into n (n: natural number).